U.S. Pat. No. 6,126,930, the entire disclosure of which is incorporated herein by reference, describes sprayable sunscreen and other topical pharmaceutical compositions which contain a substantial amount of alcohol. Normally included in such compositions is a small but suitable amount of film forming polymer, which forms a protective coating to resist loss of the active ingredient through contact with water (“water resistance”) or other physical contact (“rub-off resistance”).
Increasingly popular products of this type are sprayable sunscreens. In addition to their alcohol carriers and film forming polymers, these products also contain sunscreen additives, i.e., compounds capable of absorbing or reflecting harmful radiation from the sun, as well as optional ingredients such as emollients, perfumes and the like.
Currently, the film forming polymers of choice in such products are acrylic based, especially acrylamide based polymers. This is because such polymers are not only readily soluble in alcohol but also provide a desirable tactile sensation. On the other hand, these polymers are not biodegradable as they are synthetic and petroleum based. In addition, they are not inexpensive. Accordingly, it would be desirable to provide new sprayable, alcohol based sunscreen compositions which are made with film forming polymers which are naturally-occurring, biodegrade, and less expensive than the acrylic polymers currently being used.